1. Field
Aspects of embodiments of the present invention relate to a pixel and an organic light emitting display device using the same.
2. Description of the Related Art
With the development of information technology (IT), importance of a display device that is a connection medium between a user and information is spotlighted. Therefore, use of flat panel displays (FPDs), such as liquid crystal display devices (LCDs), organic light emitting display devices, and plasma display panels (PDPs) is increasing.
In the FPD, the organic light emitting display device displays an image by using organic light emitting diodes (OLEDs) that generate light components by re-combination of electrons and holes. The organic light emitting display device has a high response speed and has low power consumption.
The organic light emitting display device includes a plurality of data lines and scan lines and a plurality of pixels arranged in a matrix at crossing regions of power source lines. Each of the pixels is commonly formed of an OLED, two or more transistors including a driving transistor, and one or more capacitors.
The organic light emitting display device has small power consumption. However, an amount of current that flows to the OLED changes in accordance with a deviation in threshold voltage of the driving transistor included in each of the pixels so that non-uniformity in display is caused. Therefore, a method of compensating for the threshold voltage of the driving transistor while diode connecting the driving transistor is suggested.
However, when the driving transistor is diode connected, current paths are formed between a gate electrode of the driving transistor and an initializing power source and a common node between a first power source ELVDD and the OLED and the gate electrode of the driving transistor.
Here, flow of current to the current path between the common node and the gate electrode of the driving transistor is controlled in response to a voltage of a data signal. That is, when a low grayscale data signal having a high voltage is supplied, current flows from the gate electrode of the driving transistor to the common node and, when a high grayscale data signal having a low voltage is supplied, current flows from the common node to the gate electrode of the driving transistor.
Therefore, when the low grayscale data signal is supplied to a pixel, brightness increases with the lapse of time and, when the high grayscale data signal is supplied to a pixel, brightness is reduced with the lapse of time. In particular, when the pixel is driven at a low frequency (e.g., 20 Hz) in order to reduce power consumption, non-uniformity in brightness, which is caused by increase and reduction in the brightness, becomes severe.